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Aims: Monocytes/macrophages response plays a key role in postinfarction inflammation that contributes greatly to postinfarction ventricular remodelling and cardiac rupture. Therapeutic targeting of the GABAa receptor, which is enriched in monocytes/macrophages but not expressed in the myocardium, may be possible after myocardial infarction (Ml). Methods and results:After Ml was induced by ligation of the coronary artery, C57BL/6 mice were intraperitoneally administered with and results one specific agonist or antagonist of the GABAA receptor (topiramate or bicuculline), in the setting of presence or depletion of monocytes/macrophages. Our data showed that within the first 2 weeks after Ml, when monocytes/macrophages dominated, in contrast with bicuculline, topiramate treatment significantly reduced Ly-6Chigh monocyte numbers by regulating splenic monocytopoiesis and promoted foetal derived macrophages preservation and conversion of M1 to M2 or Ly-6Chigh to Ly-6Clow macrophage phenotype in the infarcted heart, though GABAAergic drugs failed to affect M1/M2 or Ly-6Chigh/Ly-6Clow macrophage polarization directly. Accordingly, proinflammatory activities mediated by M1 or Ly-6Chigh macrophages were decreased and reparative processes mediated by M2 or Ly-6Clow macrophages were augmented. As a result, post-infarction ventricular remodelling was attenuated, as reflected by reduced infarct size and increased collagen density within infarcts. Echocardiography indices, mortality and rupture rates were reduced. After depletion of monocytes/macrophages by clodronate liposomes, GABAAergic drugs exhibited no effect on cardiac dysfunction and surrogate clinical outcomes. Conclusion: Control of the GABAA receptor activity in monocytes/macrophages can potently modulate post-infarction inflammation. Topiramate emerges as a promising drug, which may be feasible to translate for Ml therapy in the future. [ABSTRACT FROM AUTHOR]

TRPM4 forms a non-selective cation channel activated by internal Ca2+. Its functional expression was demonstrated in cardiomyocytes of several mammalian species including humans, but the channel is also present in many other tissues. The recent characterization of the TRPM4 inhibitor 9-phenanthrol, and the availability of transgenic mice have helped to clarify the role of TRPM4 in cardiac electrical activity, including diastolic depolarization from the sino-atrial node cells in mouse, rat, and rabbit, as well as action potential duration in mouse cardiomyocytes. In rat and mouse, pharmacological inhibition of TRPM4 prevents cardiac ischaemia-reperfusion injuries and decreases the occurrence of arrhythmias. Several studies have identified TRPM4 mutations in patients with inherited cardiac diseases including conduction blocks and Brugada syndrome. This review identifies TRPM4 as a significant actor in cardiac electrophysiology. [ABSTRACT FROM AUTHOR]